PMC

Cumulative frequencies of DLMO for the students before and after the orange glasses intervention.

The spectral irradiance distribution (SIR) of daylight varies continuously throughout the day at every location on the earth. Shown here is the relative SIR of one, standard phase of daylight (left ordinate), defined by CIE as illuminant D65 () to represent natural daylight at 6500 K. Also shown is the spectral transmittance of the orange glasses (amber/orange, UV Process Supply), in percent (right ordinate) used in the study. Irrespective of the actual and highly variable SIR in daylight present in Smith Middle School during the experiment, the orange glasses would have attenuated all short-wavelength light from both the natural and the electric sources seen by the students.